Cancer treatment using external beam radiation therapy is a common and growing method of treatment for patients with many kinds of cancers. In almost all of these patients, cancerous tissue lies adjacent to healthy tissue, which often contains important organs, nerves, and other structures that can be exquisitely sensitive to radiation injury. Therefore, during the course of treatment great care must be taken to spare normal tissue and only irradiate the cancerous tissue.
The treatment process using external beam radiation therapy is complex and exacting. It almost always entails multiple treatments given over several weeks to complete the course of therapy. Because of this, the patient must be positioned and re-positioned accurately for each radiation therapy treatment to ensure that the proper radiation dose is delivered only to diseased tissue, and to spare the normal tissue as much as possible.
To this end, a number of devices have been developed to ensure the exact positioning of the patient. Many of these positioning devices rely on the use of a form-fitting low-melt thermoplastic “mask” of the patient's head, head and shoulders, or other body anatomy to hold the patient in exactly the same position time after time, thus ensuring that there is no patient movement during the treatment process.
The use of such devices has become commonplace in the industry. They are considered “disposable”, i.e., intended for single patient use only, and are meant to be discarded after the patient completes their course of therapy. They are formed of an injection molded, non-thermoplastic frame bonded to the sheet of low-melt thermoplastic. The form-fitting mask is typically made by heating the low-melt thermoplastic in a water bath until the material becomes pliable. It is then removed from the water bath, and then draped over the patient's face or torso and pressed to conform tightly to the patient's anatomy. As the material cools, it again becomes stiff and rigid, and thereby immobilizes the patient for his/her course of radiation therapy.
A common complaint with patients treated in this manner is that the set-up time, i.e. the time required to position the patient accurately for treatment, is time consuming and thus costly. It is therefore desirable to speed up and simplify the set-up process to increase treatment accuracy and patient throughput.
All current disposable low-melt thermoplastic masks must be locked down to the patent restraint system being used via some form of clamping mechanism. Current devices utilize screw-down clamps and other similar devices to affix the mask to the restraint board. Some other systems use a non-disposable holder into which the disposable thermoplastic mask is placed and secured, either by screw-clamps or “snap fit” mechanisms; this holder is then clamped to the restraint board using mechanisms similar to those described above.
In all of these cases the thermoplastic mask itself does not possess any mechanism that allows it to be easily and securely affixed to the treatment board. All must be attached to the treatment board in a laborious and time-consuming fashion, requiring several radiation technologists (those folks responsible for patient setup) be involved in the set-up process.